Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

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Until recently, a planet-wide state of quarantine seemed almost unimaginable,

but in the future, could entire planets be quarantined from the rest of space,

and what dreadful causes could necessitate such measures?

Welcome back to SFIA for another sci-fi Sunday, where we examine concepts we see in

science fiction and try to bring some science and realism to them.

Today, our target is quarantine worlds, if they would exist and why, how you might enforce

such quarantines, and what life on one might

be like.

The first question would seem the easiest to answer, since we are talking about an entire

inhabited planet, and our only example of that is Earth itself, which may not be quarantined,

but on which we can't exactly escape from yet.

As we'll see, though, especially

when we start considering planets underdevelopment, or inhabited moons or major space habitats,

that changes quite a lot. And as we contemplated in our recent episode on pan-cosmorial theory,

many planets might be terribly vulnerable to being cut off from outside civilization.

Quarantine hypothesis is the concept in discussion of the Fermi paradox that Earth might

be in a quarantine itself, and it raises the question of what sort of motivation of quarantine

you have.

...